Effects of fibers on expansive shotcrete mixtures consisting of calcium sulfoaluminate cement,ordinary Portland cement,and calcium sulfate

The mining industry often uses shotcrete for ground stabilization. However, cracking within shotcrete is commonly observed, which delays production schedules and increases maintenance costs. A possible crack reduction method is using expansive shotcrete mixture consisting of calcium sulfoaluminate cement (CSA), ordinary Portland cement (OPC), and calcium sulfate (CS) to reduce shrinkage. Furthermore, fibers can be added to the mixture to restrain expansion and impede cracking. The objective of this paper is to study the effects of nylon fiber, glass fiber, and steel fiber on an expansive shotcrete mixture that can better resist cracking. In this study, parameters such as density, water absorption, volume of permeable voids, unconfined compressive strength (UCS), splitting tensile strength (STS), and volume change of fiber-added expansive mixtures were determined at different time periods (i.e. the strengths on the 28th day, and the volume changes on the 1st, 7th, 14th, 21st, and 28th days). The results show that addition of fibers can improve mixture durability, in the form of decreased water absorption and reduced permeable pore space content. Moreover, the expansion of the CSA-OPC-CS mixture was restrained up to 50% by glass fiber, up to 43% by nylon fiber, and up to 28% by steel fiber. The results show that the STS was improved by 57% with glass fiber addition, 43% with steel fiber addition, and 38% with nylon fiber addition. The UCS was also increased by 31% after steel fiber addition, 26% after nylon fiber addition, and 16% after glass fiber addition. These results suggest that fiber additions to the expansive shotcrete mixtures can improve durability and strengths while controlling expansion.     

Influence of some organic and inorganic additives on pressure-driven purification of waters containg cobalt

The paper has investigated the possibility of using polyelectrolyte and clayey minerals in processes of pressure-driven purification of waters polluted by Co(II). Determined the impact of ionic force of the solution on removal of Co(II) by the method of reverse osmosis. It has been shown that the use of montmorillonite in pressure-driven processes of water purification containing cobalt is effective and promising.     

硫酸钙污泥基胶凝材料的制备及性能研究

以硫酸钙污泥为主要掺合料制备硫酸钙污泥基胶凝材料并对其性能进行测试,通过单因素试验研究了不同掺合料对胶凝材料细度、流动度比和活性指数的影响。结果表明:在标准养护条件下,采用20%污泥灰+80%矿粉制备的复合掺合料性能较好,当此复合掺合料掺量为30%,胶砂比为1∶3,水胶比为0.5时,硫酸钙污泥基胶凝材料的28 d活性指数为95.11%,细度为7.34%,流动比为111.6%,符合JG/T 486—2015中普通型Ⅰ级要求,是一种性能良好的胶凝材料。     

Effects of chloride,sulfate and natural organic matter (NOM) on the accumulation and release of trace-level inorganic contaminants from corroding iron

This study examined effects of varying levels of anions (chloride and sulfate) and natural organic matter (NOM) on iron release from and accumulation of inorganic contaminants in corrosion scales formed on iron coupons exposed to drinking water. Changes of concentrations of sulfate and chloride were observed to affect iron release and, in lesser extent, the retention of representative inorganic contaminants (vanadium, chromium, nickel, copper, zinc, arsenic, cadmium, lead and uranium); but, effects of NOM were more pronounced. DOC concentration of 1 mg/L caused iron release to increase, with average soluble and total iron concentrations being four and two times, respectively, higher than those in the absence of NOM. In the presence of NOM, the retention of inorganic contaminants by corrosion scales was reduced. This was especially prominent for lead, vanadium, chromium and copper whose retention by the scales decreased from >80% in the absence of NOM to <30% in its presence. Some of the contaminants, notably copper, chromium, zinc and nickel retained on the surface of iron coupons in the presence of DOC largely retained their mobility and were released readily when ambient water chemistry changed. Vanadium, arsenic, cadmium, lead and uranium retained by the scales were largely unsusceptible to changes of NOM and chloride levels. Modeling indicated that the observed effects were associated with the formation of metal–NOM complexes and effects of NOM on the sorption of the inorganic contaminants on solid phases that are typical for iron corrosion in drinking water.     

Natural waste materials containing chitin as adsorbents for textile dyestuffs: batch and continuous studies

In this work three natural waste materials containing chitin were used as adsorbents for textile dyestuffs, namely the Anodonta (Anodonta cygnea) shell, the Sepia (Sepia officinalis) and the Squid (Loligo vulgaris) pens. The selected dyestuffs were the Cibacron green T3G-E (CI reactive green 12), and the Solophenyl green BLE 155% (CI direct green 26), both from CIBA, commonly used in cellulosic fibres dyeing, the most used fibres in the textile industry. Batch equilibrium studies showed that the materials' adsorption capacities increase after a simple and inexpensive chemical treatment, which increases their porosity and chitin relative content. Kinetic studies suggested the existence of a high internal resistance in both systems. Fixed bed column experiments performed showed an improvement in adsorbents' behaviour after chemical treatment. However, in the column experiments, the biodegradation was the main mechanism of dyestuff removal, allowing the materials' bioregeneration. The adsorption was strongly reduced by the pore clogging effect of the biomass. The deproteinised Squid pen (grain size 0.500-1.41 mm) is the adsorbent with highest adsorption capacity (0.27 and 0.037 g/g, respectively, for the reactive and direct dyestuffs, at 20 degrees C), followed by the demineralised Sepia pen and Anodonta shell, behaving like pure chitin in all experiments, but showing inferior performances than the granular activated carbon tested in the column experiments.     

Traditional organic additives improve lime mortars: New old materials for restoration and building natural stone fabrics

Portland cement has low chemical and physical affinity for traditional building materials. This hinders the restoration of historical buildings and modern rustic architecture where natural stone is used. Lime mortars used in construction since c.12,000 B.C. were recovered, and attempts were made to enhance their properties. Various additives were selected on the basis of their properties and historical use. These include polysaccharides (opuntia, also known as nopal used either as a powder or as mucilage), proteins (animal glue and casein) and fatty acids (olive oil). Six types of lime mortar were formulated and characterized. Compressive strength, water-resistance, carbonation speed, porosity, texture and mineral composition were measured. We propose new lime mortars with added value, i.e. increased mechanical properties and water-resistance, different carbonation speeds, and different textures. They are all compatible with traditional building materials, so they can be used in the restoration of architectural heritage and modern architecture where natural stone is used.     

Release of PAHs from solidified recycled construction materials and solid waste

Diffusive contaminant fluxes from subsurface construction materials as well as from solidified waste and recycled materials (e.?g. demolition waste) can lead to significant long-term input of contaminants into seepage water or groundwater. Demolition waste, sandy soil material and asphalt granulates were solidified and investigated in a modified tank diffusion test to determine the PAH fluxes (F) under maximum concentration gradients. Using a parameter fitting routine, the apparent diffusion coefficients (D _a ) were determined. Fluxes (F) were determined at different temperatures and evaluated using the Arrhenius relationship to determine the activation energy (?E _a ). A temperature decrease of 10?°C typically decreases the contaminant fluxes by 50?%. D _a and ?E _a are constants for given contaminant loadings and can be determined easily with the modified batch diffusion experiment. D _a and ?E _a allow the calculation of contaminant releases for real case subsurface structures at given temperatures. Average concentrations in groundwater depend on time period, flow velocity, and averaged water volume.     

Seawater induced release and transformation of organic and inorganic phosphorus from river sediments

This paper reports an investigation of the release of organic and inorganic phosphorus from a riverine sediment subjected to salinity conditions typical of estuarine mixing. Freshwater sediment was mixed with filtered river water in a thermostatted reactor, and allowed to equilibrate under aerobic conditions for 3 days. Salinity was then increased in a stepwise manner by addition of filtered low-nutrient seawater over a period of 4 days. A control experiment was performed in a second reactor by substituting ultrapure water for seawater. Using a flow injection analysis method for measurement of filterable reactive phosphorous (FRP, the so-called inorganic fraction) and filterable organic phosphorous (FOP), it was found that rapid releases of both FOP and FRP occurred at salinities of >/=10 per thousand. Over the 4-day experimental period, sediment release increased the filterable P concentration by approx. 50 microgL(-1), and of this, nearly half was initially present as FOP, which subsequently underwent rapid mineralisation to FRP. The observed behaviour may be explained by a combination of salinity induced plasmolysis of sediment bacteria and ion exchange by suspended sediment particles.     

Removing metals from waste solutions with low rank coals and related materials

Ion exchange media were produced by contacting brown coal, peat or wood sawdust with a solution of calcium hydroxide, preferably as an aqueous slurry of lime. The resultant calcium loading on the media, which ranged up to 8% for sawdust, 12% for peat and to 19% for brown coal, was exchanged for many metals in solution.Preliminary work showed the method to be amenable to extraction of copper, nickel, chromium, cadmium, lead, zinc, mercury, cobalt, silver, iron, manganese, vanadium, germanium, gallium, aluminium, antimony and uranium. For most of the metals more than 99% was removed from I g 1⁻¹ solutions.In more detailed work, confined to calcium loaded brown coal and solutions having metal concentrations more typical of industrial operations, minimum residual metal concentrations of 0.0005 mg l⁻¹ mercury; 0.02 mg 1⁻¹ copper; 0.02 mg 1⁻¹ zinc; <0.05 mg l⁻¹ cadmium; 0.1 mg 1⁻¹ lead and 0.2 mg l⁻¹ manganese were obtained. These results compare favourably with those reported for other relevant processes and there might be operational advantages in the method.The method can be applied either by agitating the calcium loaded media in the solution and then filtering, or by passing the solution through packed beds of the media. Where appropriate, dilute solutions can be up-graded for re-use by stripping the metals from the media which can also be re-used. Alternatively, the loaded media can be combusted and the metals recovered from the residues.The method might be applicable to mine drainage and to effluents from metallurgical processing and electroplating, but more work is required to assess costs.It is suggested that the method is environmentally preferable to other common effluent treatment procedures because it enables collection and recycling of heavy metal pollutants.     

Application of the partition-limited model for plant uptake of organic chemicals from soil and water

This study further examined the merits of the partition-limited model for the plant uptake of organic chemicals from soil and water. The influential factors on the quasi-equilibrium factor (alpha(pt)) of the model were evaluated for a number of systems. The present study manifested a generally high efficiency of the model for prediction of phenanthrene and pyrene uptake by plants. The overall model predictions are within an order of magnitude of the measured values, with the differences between the estimated and measured concentrations being less than 93.7% in most cases. Modeled root concentrations seemed to be more accurate than modeled shoot concentrations. Generally, the calculated alpha(pt) values for plant uptake of chemicals from water, including phenanthrene and pyrene on basis of our experimental data and lindane and trifluralin on basis of the available literature data, tend to be relatively constant after an initial fast increase with increasing uptake time. alpha(pt) values for root uptake of these chemicals are always greater than those for shoot uptake. In addition, alpha(pt) values for various root uptake of hydrophobic chemicals, e.g., phenanthrene and pyrene, exhibit significantly positive correlations with root lipid contents (p < 0.05, n = 10). This investigation substantiated the concept of the partition-limited model and its utility for vegetation-uptake assessment.     

含BTEX三甘醇再生废气的回收利用

三甘醇脱水工艺是天然气工业中应用最早也最为普遍的一种方法。通常,采用气提再生对三甘醇贫液进行提浓,使得外输干气水露点达到环境要求。目前,由于三甘醇脱水工艺中再生废气采用直接排放的方式,当天然气中含有BTEX组分时,对环境与生产人员造成极大的危害。通过HYSYS模拟,论证了三甘醇脱水典型工艺流程,再生废气经过冷凝后回收用作气提气的改进工艺与DRIZO脱水工艺。分析得出,DRIZO脱水工艺脱水效果好,能耗低且能显著降低BTEX的排放,有效解决了再生废气的污染及三甘醇损失等问题,具有较高的推广价值。     

表面预处理及混凝土回收骨料的试验研究

本文研究了表面预处理骨料和混凝土回收骨料对混凝土力学性能的影响,并对混凝土回收分离设备的质量控制参数提出了要求,分析了这类骨料引起混凝土强度变化的原因.     

Pressure development during explosions in clouds of dusts from grain, feedstuffs and other natural organic materials

An investigation into the explosibility of dusts from a range of grain and feedstuffs has been undertaken. The standard Hartmann bomb was used as test apparatus, the ignition source being a continuous spark.The purpose of the investigation was two-fold. First, it was of interest to analyze the statistical scatter in data from replicate Hartmann bomb tests. Secondly, it was desirable to disclose any systematic relationship existing between explosibility, and physical and chemical properties of the dusts.The statistical analysis revealed that the coefficients of variation, σ/m, of p_max in replicate tests with a given dust, were for most of the dusts between 0.05 and 0.10, whereas in the case of (dp/dt)_max most of the coefficients of variation were between 0.20 and 0.40. Further statistical analysis indicated that distributions of data from replicate Hartmann bomb test scan be assumed to be normal.No systematic correlation between calorific values of the dusts and explosibility was found.The possibility of correlating explosibility to chemical composition as obtained in a standard Weende feedstuffs analysis, was investigated. A reasonably good positive correlation between (dp/dt)_max and percentage starch + fibres (cellulose) was disclosed. Results from additional Hartmann bomb tests with starch, cellulose and protein powders confirmed the validity of this correlation. The goodness of the correlation was improved when taking into account the effect of variations in particle size, expressed as specific “envelope” surface.The effect of moisture content in the dust, on (dp/dt)_max was also investigated. A simple relationship, likely to be applicable to the group of dusts studied, was found.The results obtained can be condensed into an approximative, empirical equation, applicable to the group of dusts studied, and giving, at a selected probability level of confidence, (dp/dt)_max in a Hartmann bomb test as a function of chemical composition, moisture content, and fineness of the dust.     

Characteristics of mortar and concrete containing fine aggregate manufactured from recycled waste polyethylene terephthalate bottles

This paper presents the development of lightweight aggregate concrete using fine aggregate that is manufactured from recycled waste polyethylene terephthalate (PET) bottles. Investigations on waste PET lightweight aggregate concrete included three phases: examination of the properties of waste PET lightweight aggregates (WPLA), analysis of the properties of mortar when WPLA was used as fine aggregate, and analysis of the properties of concrete when WPLA was used as fine aggregate. The results of the first phase showed that the WPLA had a density of 1390 kg/m³, a water absorption of 0% and a bulk density of 844 kg/m³. WPLA fineness modulus (F.M.), however, was 4.11, which is higher than the F.M. of river sand. This is because the WPLA was single graded. The results of the second phase showed that for the mortar, in which the WPLA was used as a fine aggregate, the flow value increased, while the compressive strength decreased proportionally to the addition of WPLA with elapsed time. In addition, the amount of water absorption by unit area was higher than for the control mortar (without WPLA) when the WPLA content was either 40% or 60%. For the third phase, the results showed that the slump of the WPLA concrete increased as the WPLA content increased regardless of the water-cement ratio (W/C). In comparison to the control concrete, the 28-day WPLA concrete compressive strength decreased by 5%, 15% and 30%, with an increase of WPLA content of 25%, 50% and 75%, respectively. In addition, for a W/C of 0.49, the structural efficiency (compressive strength/density ratio) of the concrete containing 25% of WPLA was higher than that for the control concrete.     

Ionic liquids for extraction of metals and metal containing compounds from communal and industrial waste water

In a fundamental study the potential of ionic liquids based on quaternary ammonium- and phosphonium cations and thiol-, thioether-, hydroxyl-, carboxylate- and thiocyanate-functionalized anions has been assessed for future application in advanced sewage treatment. The elimination of the metal(oid)s Ag, As, Cd, Cr, Cu, Hg, Ni, Pb, Pt, Sn, Zn and the cancerostatic platinum compounds cisplatin and carboplatin was screened using a liquid phase micro-extraction set-up. The analytical tool-set consisted of ICP-SFMS and LC-ICP-MS for quantification of metal(oid)s and cancerostatic platinum compounds, respectively. The purity of the ILs was assessed for the investigated metal(oid)s on the base of present EU environmental quality standards and was found to be sufficient for the intended use. In model solutions at environmental relevant concentrations extraction efficiencies ≥95% could be obtained for Ag, Cu, Hg and Pt with both phosphonium- and ammonium-based ILs bearing sulphur functionality in the form of thiosalicylate and 2-(methylthiobenzoate) anions, as well as with tricaprylmethylammonium thiocyanate within an extraction time of 120 min. All other metals were extracted to a lower extent (7-79%). In the case of cancerostatic platinum compounds a phosphonium-based IL bearing thiosalicylate functionality showed high extraction efficiency for monoaquacisplatin.For the first time, liquid phase micro extraction with ionic liquids was applied to industrial and communal waste water samples. The concentration of all investigated metal(oid)s could be significantly reduced. The degree of elimination varied with the initial concentration of metals, pH and the amount of suspended particulate matter.     

Production of polyhydroxyalkanoates in open, mixed cultures from a waste sludge stream containing high levels of soluble organics, nitrogen and phosphorus

In this study, the production of polyhydroxyalkanoates (PHAs) from waste activated sludge (WAS) was evaluated. PHAs were produced from fermented WAS pretreated via high-pressure thermal hydrolysis, a stream characterised by high levels of nutrients (approximately 3.5 g N L⁻¹ and 0.5 g P L⁻¹) and soluble organics. PHA-storing organisms were successfully enriched at high organic loading rates (6 g COD_sol L⁻¹ d⁻¹) under aerobic dynamic feeding in sequencing batch reactors at a sludge retention time of 6 d with a short feast length less than 20% of the cycle, and a maximum substrate concentration during feast of 1 g COD_VFA L⁻¹. The biomass enrichment, characterised by a decrease in species evenness based on Lorenz curves, provided a biomass that accumulated 25% PHA on a dry-biomass basis with yields on VFA of 0.4 Cmol Cmol⁻¹ in batch tests. The PHA consisted of ∼70 mol% 3-hydroxybutyrate and ∼30 mol% 3-hydroxyvalerate, and presented high thermal stability (T_d = 283-287 °C) and a molecular mass ranging from 0.7 to 1.0 × 10⁶ g mol⁻¹. Overall PHA storage was comparable to that achieved with other complex substrates; however, lower PHA storage rates (0.04-0.05 Cmol PHA⁻¹ Cmol X⁻¹ h⁻¹) and productivities (3-4 Cmol PHA L⁻¹ h⁻¹) were probably associated with a biomass-growth and high-respiration response induced by high levels of non-VFA organics (40-50% of COD_sol in feed) and nutrients. PHA production is feasible from pretreated WAS, but the enrichment and accumulation process require further optimisation. A milder WAS pretreatment yielding lower levels of non-VFA organics and readily available nutrients may be more amenable for improved performance.     

Occurrence and alteration of organic contaminants in seepage and leakage water from a waste deposit landfill

Organic-geochemical analyses have been applied to seepage water and leakage water samples of a waste deposit landfill in order to give a comprehensive view on the composition of the organic contaminants. Based on intense GC/MS screening analyses a wide variety of organic substances were identified and attributed to natural or xenobiotic waste components. Apart from plant material-derived compounds and degradation products of peptides, carbohydrates and lignin, numerous xenobiotic substances were identified and attributed to the groups of pharmaceuticals, plasticizers, pesticides or chlorinated aromatics. Not all of the substances identified in the seepage water samples were recovered in the leakage water sample due to degradation processes or dilution by uncontaminated water. Quantitative analysis of selected contaminants was used to discriminate substances affected by degradation processes and persistent compounds.     

Solubility of organic chemicals in octanol, triolein and cod liver oil and relationships between solubility and partition coefficients

The solubilities of 54 chemicals were measured in octanol, triolein and cod liver oil. Solubility of most chemicals increased with temperature between 4 and 20°C. Values of solubility in water and octanol/water partition coefficient (K_ow) for these chemicals were compiled from the literature to examine their relationships with solubility in the three solvents. Regression analyses indicated highly significant relationships between (1) the chemicals' solubility in water and the three solvents, (2) solubility in water and K_ow, (3) solubility in other solvents and K_ow and (4) solubility ratio of solvent/water and K_ow. Relationships 2–4 tend to be less well defined with increasing K_ow, this responses may be attributed to K_ow values that were derived by extrapolation or calculation. Further analyses between log solubility ratios and log K_ow values up to 5.0, indicate a linear relationship where the regression coefficient was not significantly different from 1.0, and a regression intercept that included zero. This response would suggest K_ow could be calculated from the solubility ratios of chemicals that are not miscible in solvents.     

Removal of inorganic mercury and methylmercury from surface waters following coagulation of dissolved organic matter with metal-based salts

The presence of inorganic mercury (IHg) and methylmercury (MeHg) in surface waters is a health concern worldwide. This study assessed the removal potential use of metal-based coagulants as a means to remove both dissolved IHg and MeHg from natural waters and provides information regarding the importance of Hg associations with the dissolved organic matter (DOM) fraction and metal hydroxides. Previous research indicated coagulants were not effective at removing Hg from solution; however these studies used high concentrations of Hg and did not reflect naturally occurring concentrations of Hg. In this study, water collected from an agricultural drain in the Sacramento-San Joaquin Delta was filtered to isolate the dissolved organic matter (DOM) fraction. The DOM was then treated with a range of coagulant doses to determine the efficacy of removing all forms of Hg from solution. Three industrial-grade coagulants were tested: ferric chloride, ferric sulfate, and polyaluminum chloride. Coagulation removed up to 85% of DOM from solution. In the absence of DOM, all three coagulants released IHg into solution, however in the presence of DOM the coagulants removed up to 97% of IHg and 80% of MeHg. Results suggest that the removal of Hg is mediated by DOM-coagulant interactions. There was a preferential association of IHg with the more aromatic, higher molecular weight fraction of DOM but no such relationship was found for MeHg. This study offers new fundamental insights regarding large-scale removal of Hg at environmentally relevant regarding large-scale removal of Hg at environmentally relevant concentrations.